SF.net SVN: fclient: [597] trunk/fclient/src/fclient/lib/fcp2/lib/events.py

[<jU...@us...>]

Revision: 597
          http://fclient.svn.sourceforge.net/fclient/?rev=597&view=rev
Author:   jUrner
Date:     2008-07-12 12:57:57 -0700 (Sat, 12 Jul 2008)

Log Message:
-----------
weakref observers

Modified Paths:
--------------
    trunk/fclient/src/fclient/lib/fcp2/lib/events.py

Modified: trunk/fclient/src/fclient/lib/fcp2/lib/events.py
===================================================================
--- trunk/fclient/src/fclient/lib/fcp2/lib/events.py	2008-07-12 19:57:33 UTC (rev 596)
+++ trunk/fclient/src/fclient/lib/fcp2/lib/events.py	2008-07-12 19:57:57 UTC (rev 597)
@@ -1,5 +1,6 @@
 """Signals and events"""
 
+import weakref
 #*********************************************************************
 #
 #*********************************************************************
@@ -81,7 +82,8 @@
 	"""Event class
 	
 	@ivar name: name of the event
-	@ivar observers: observers listening to the event
+	@note: only a weak reference is kept observers to automatically remove observers when
+	the observer is no longer alive
 	
 	>>> event = Event('myEventsName')
 	>>> event.name
@@ -101,40 +103,41 @@
 		@param name: name of the event
 		"""
 		self.name = name
-		self.observers = []
+		self._refs = []
 		
+		
 	def __call__(self, *args, **kwargs):
 		"""Dispatches the event and additional parameters to all observers registerd
 		
 		@note: all listeners will be called with the event a first parameter, followed 
 		by optional args and kwargs
 		"""
-		for observer in self.observers: 
-			observer(self, *args, **kwargs)
-		
-	def __contains__(self, observer):
-		"""Checks if an observer is aleady registered
-		@return: bool
-		"""
-		return observer in self.observers
-			
+		for ref in self._refs: 
+			observer = ref()
+			if ref is not None:
+				observer(self, *args, **kwargs)
+					
 	def __iadd__(self, observer):
 		"""Adds an observer to the event
 		@note: the observer will be called with the event as first paraeter,
 		followed by any number of *args or **kwargs passed by the caller of an event
 		"""
-		self.observers.append(observer)
+		self._refs.append(weakref.ref(observer, self.handleDereference))
 		return self
 	
 	def __isub__(self, observer):
 		"""Removes the first occurence of an observer from the event"""
-		self.observers.remove(observer)
+		observers = [i() for i in self._refs]
+		del self._refs[observers.index(observer)]
 		return self
+
+	def handleDereference(self, ref):
+		self._refs.remove(ref)
 		
 #*********************************************************************
 #
 #*********************************************************************
 if __name__ == '__main__':
 	import doctest
-	doctest.testmod()
+	print 'doctests failed: %s/%s' % doctest.testmod()
 


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